This invention relates to a printing machine for printing characters on paper sheets, and more particularly to a printing machine which is capable of selectively or simultaneously printing characters on two kinds of paper sheets.
A printing machine of this type is loaded with a long paper sheet such as journal paper and a short paper sheet such as slips. The long paper sheet is continuously supplied and is cut at an arbitrary position after a necessary amount of printing has been completed. Therefore, the length of the cut paper sheet is variable. The long paper sheet is clamped between a pinch roller and a paper feed roller in the printing machine and this long paper sheet is then fed by rotation of the paper feed roller.
On the other hand, short paper sheets of a predetermined length are loaded as need arises. After the long paper sheet is loaded, the pinch roller is separated from the paper feed roller to form a predetermined gap between the rollers. Then the short paper sheet is inserted through the gap between the pinch roller and the paper feed roller into the printing machine.
Thus, in the conventional printing machine of this type, the long paper sheet is released from its clamped condition between the pinch roller and the paper feed roller simultaneously with the loading operation of the short paper sheet. Consequently, this free long paper sheet is readily displaced. When this paper sheet is again clamped by the pinch and paper feed rollers, it may be held in an improper position or in an inclined condition, which has been one of the defects of such a conventional printing machine.